Ooh, interesting, an encyclopedia on pokemon... Though I do respect your opinions on pokemon evolution, I've got a theory how the way seen in the games and anime would work: (Yes, I read the first post, but I just wanted to share my opinion)
Pokemon store nutrients and hormones that they need to grow inside their bodies until they are ready to grow- this unleashing of the stored hormones and nutrients and growing and maturing very quickly(in a matter of seconds) is referred to as an evolution. It is often associated with a lighter colour or even glow on the pokemons body because of the fast and costant changes happening so quickly that the body doesn't have time to reform until the event is over. Some pokemon still don't follow this rule-radiation from certain element stones might trigger a mutation in a pokemon(example:Pikachu) Or an evolution changing only a part of a pokemon(example:Bulbasaur).
What do you think? Oh, and could I do some articles, too?